Electricity production and treatment of high-strength dairy wastewater in a microbial fuel cell using acclimated electrogenic consortium

Abstract

Microbial fuel cells are innovative technologies that can efficiently remove chemical oxygen demand and biochemical oxygen demand, while simultaneously generating electricity, with a minimal environmental footprint. High efficiencies have recently been achieved for the treatment of low-strength wastewater. However, in treatment of a real high-strength wastewater, such as dairy effluent, the efficiency decreases drastically due to operational instability associated with environmental fluctuations, difficulty of maintaining the run for long periods, and fouling. In order to overcome these issues, a new initialization method was developed, with a start-up phase employing an inoculum composed of a consortium of fermenting and metal-reducing bacteria, followed by acclimation and treatment phases. The protocol employed enabled removal of 90% of total biochemical oxygen demand, 62% of total chemical oxygen demand, 72% of total Kjeldahl nitrogen, 71% of sodium, and 65% of ultraviolet absorbing substances from dairy wastewater. Furthermore, the microbial fuel cell produced maximum power densities of 1.45 W/m3 in the acclimation phase and 1.32 W/m3 in the treatment phase. The findings demonstrated that microbial fuel cells powered by real high-strength dairy wastewater can achieve high efficiencies.